look here!

Jeff,
What foam did you end up getting? The pour or injection?

Jeff, there's and old write-up about this with pics somewhere on here. Pete, did you post it? Brady? I know there's some discussion in the patch. Anyway, I had this decision to make as well. I used the pour meathod mostly because I stayed with the factory build. If you want the ply floor either way, then the injection meathod makes good sense. Be forwarned though; that stuff is gonna do what it's gonna do.

A few points:

-pour foam can be hectic and you'll want a helper
-pour foam is a little cheaper and I used a good bit more than expected
-inj foam should be close to zero waste
-inj foam will make its own skin except at the hole(s); I'd cut more than 1
-either way, a good bit of epoxy goes down before the first glass and that makes a darn good replacement skin

What is your concern about wrecking earlier work?

Jeff,
All you need is one hole to get the guns extension into the cavity. 1&1/2" is fine. The pressure isn't alot unless you overfill the cavity. Start filling at the farthest spot from the hole. Do it in stages allowing about 10 seconds between the "shots" for the foam to expand. Once you get a feel for how fast and how much, it will be easy!

As long as your ply isn't real thin (under 1/2"), then the small distance between it's bonds/supports will keep it from bulging. You could place a concrete block in the middle, but I do not feel you will have a problem. You have/will be epoxy bonding the ply down correct?

And yes thick floor 3/4 ply, also thick mat under floor for seat mounting screws, thx for the idea Benj!

Thanks Pete! going to move forward on the foaming this week.